This invention relates to a process for preparing long chain alkyl phenols by alkylating an aromatic compound with a relatively long chain alkylating agent employing a synthetic porous crystalline material, or zeolite, as alkylation catalyst.
Zeolite materials, both natural and synthetic, have been demonstrated in the past to have catalytic properties for various types of hydrocarbon conversion. Certain zeolite materials are ordered, porous crystalline aluminosilicates having a definite crystalline structure as determined by X-ray diffraction, within which there are a large number of smaller cavities which may be interconnected by a number of still smaller channels or pores. These cavities and pores are uniform in size within a specific zeolitic material. Since the dimensions of these pores are such as to accept for adsorption molecules of certain dimensions while rejecting those of larger dimensions, these materials have come to be known as "molecular sieves" and are utilized in a variety of ways to take advantage of these properties. Such molecular sieves, both natural and synthetic, include a wide variety of positive ion-containig crystalline silicates. These silicates can be described as a rigid three-dimensional framework of SiO.sub.4 and Periodic Table Group IIIA element oxide, e.g., AlO.sub.4, in which the tetrahedra are cross-linked by the sharing of oxygen atoms whereby the ratio of the total Group IIIA element, e.g., aluminum, and silicon atoms to oxygen atoms is 1:2. The electrovalence of the tetrahedra containing the Group IIIA element, e.g., aluminum, is balanced by the inclusion in the crystal of a cation, e.g., an alkali metal or an alkaline earth metal cation. This can be expressed wherein the ratio of the Group IIA element, e.g., aluminum, to the number of various cations, such as Ca/2, Sr/2, Na, K or Li, is equal to unity. One type of cation may be exchanged either entirely or partially with another type of cation utilizing ion exchange techniques in a conventional manner. By means of such cation exchange, it has been possible to vary the properties of a given silicate by suitable selection of the cation. The spaces between the tetrahedra are occupied by molecules of water prior to dehydration.
Prior art techniques have resulted in the formation of a great variety of synthetic zeolites. Many of these zeolites have come to be designated by letter or other convenient symbols, as illustrated by zeolite Z (U.S. Pat. No. 2,882,243); zeolite X (U.S. Pat. No. 2,882,244); zeolite Y (U.S. Pat. No. 3,130,007); zeolite ZK-5 (U.S. Pat. No. 3,247,195); zeolite ZK-4 (U.S. Pat. No. 3,314,752), zeolite ZSM-5 (U.S. Pat. No. 3,702,886); zeolite ZSM-11 (U.S. Pat. No. 3,709,979); zeolite ZSM-12 (U.S. Pat. No. 3,832,449); zeolite ZSM-20 (U.S. Pat. No. 3,972,983); zeolite ZSM-35 (U.S. Pat. No. 4,016,245); and zeolite ZSM-23 (U.S. Pat. No. 4,076,842), merely to name a few.
The SiO.sub.2 /Al.sub.2 O.sub.3 ratio of a given zeolite is often variable. For example, zeolite X can be synthesized with SiO.sub.2 /Al.sub.2 O.sub.3 ratios of from 2 to 3; zeolite Y, from 3 to about 6. In some zeolites, the upper limit of the SiO.sub.2 /Al.sub.2 O.sub.3 ratio is unbounded. ZSM-5 is one such example wherein the SiO.sub.2 /Al.sub.2 O.sub.3 ratio is at least 5 and up to the limits of present analytical measurement techniques. U.S. Pat. No. 3,941,871 (RE. 29,948) discloses a porous crystalline silicate made from a reaction mixture containing no deliberately added alumina in the recipe and exhibiting the X-ray diffraction pattern characteristic of ZSM-5. U.S. Pat. Nos. 4,061,724; 4,073,865 and 4,104,294 describe crystalline silicates of varying alumina and metal content.
Several long chain alkyphenols are known useful items of commerce. p-Nonylphenol, for instance, which is used primarily in the manufacture of synthetic detergents, is currently produced in quantities of about 100 million pounds a year. Production of these compounds by conventional methods, for example, by the alkylation of phenol in the presence of conventional alkylation catalysts is, however, somewhat problematic in that the reaction yields a broad spectrum of products. Isolation or enrichment of specific positional isomers is both difficult and expensive.
Traditionally, alkylation reactions are generally carried out at atmospheric pressure with the reactants in the liquid phase utilizing catalyst such as sulfuric acid, boron trifluoride, aluminum chloride or strongly acidic ion exchange resins. Some zeolites, specifically REX and HY, have been reported in the scientific literature as catalyzing the reaction of 1-decyl alcohol with phenol at atmospheric pressure and 200.degree. C. The product of that reaction was predominantly an ortho/para mixture of decyphenols with side chain attachment largely at the second and third carbon atoms of the alkyl group.
U.S. Pat. No. 4,283,573 describes a process for producing relatively long chain alkylphenols by alkylation of phenol with a long chain alkylating agent possessing one or more available alkyl groups of at least 5 carbon atoms in length employing as catalyst a zeolite such as cancrinite, gmelinite, mordenite, offretite or ZSM-12.